Grasshoppers use their strong hind legs to leap into the air. They are also able to use their wings to fly away from predators. They can use their jumping ability to give themselves a boost before flying.
Grasshoppers' hind legs function like miniature catapults. Before jumping, a grasshopper contracts its hind legs slowly and bends its hind legs at the knee joint. There is a special cuticle in the grasshopper's knee that functions as a spring. The cuticle stores up all of the potential energy. When the grasshopper is ready to go, it relaxes the leg muscles. The spring releases its energy, catapulting the grasshopper into the air.